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swiftPunk
Asked: 2024-09-03 05:50:43 +0800 CST

如何更新数组中嵌套项中的所需项？

  • 772

我想更新嵌套项目数组中的项目，为了展示问题，我在下面编写了示例代码，这个问题的重点是更新嵌套项目而不是 SwiftUI 技巧。我想找到一个知道其 id 的项目，找到后尝试更新。在下面的代码中，我向您展示了更新第一层项目的示例，但只要层数更深，我们就无法猜测它可以是 2 层还是 10 层，我们不知道。我怎样才能更新item1、item2和item4？

在此处输入图片描述

    import SwiftUI


@main
struct findItem_testApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView().environmentObject(ItemModel.shared)
        }
    }
}


    
    struct ContentView: View {
        
        @EnvironmentObject var itemModel: ItemModel
        
        var body: some View {
            
            VStack {
    
                MyView(item: itemModel.items[0])
                MyView(item: itemModel.items[1].nestedItems[0].nestedItems[0])
                MyView(item: itemModel.items[1].nestedItems[0])
                MyView(item: itemModel.items[1])
                MyView(item: itemModel.items[2].nestedItems[0])
                MyView(item: itemModel.items[2])
    
            }
    
        }
    }
    
    struct MyView: View {
        
        let item: ItemType
        
        var body: some View {
    
            Text(item.name)
                .bold()
                .padding()
                .onTapGesture {
                    print(item.name, item.id)
                    // need to update item.name from model
                    ItemModel.shared.updateName(id: item.id, value: item.name + " updated!")
                }
      
        }
    }
    
    
    
    struct ItemType: Identifiable {
    
        let id: UUID
        var name: String
        var nestedItems: [ItemType]
    
        init(name: String, nestedItems: [ItemType]) {
            self.id = UUID()
            self.name = name
            self.nestedItems = nestedItems
        }
        
    }
    
    let item0: ItemType = ItemType(name: "item0", nestedItems: [])
    
    let item1: ItemType = ItemType(name: "item1", nestedItems: [])
    let item2: ItemType = ItemType(name: "item2", nestedItems: [item1])
    let item3: ItemType = ItemType(name: "item3", nestedItems: [item2])
    
    let item4: ItemType = ItemType(name: "item4", nestedItems: [])
    let item5: ItemType = ItemType(name: "item5", nestedItems: [item4])
    
    
    class ItemModel: ObservableObject {
        
        static let shared: ItemModel = ItemModel()
        
        @Published var items: [ItemType] = [ItemType]()
        
        init() {
            self.items = [item0, item3, item5]
        }
    
        func updateName(id: UUID, value: String) {
    
            for i in (0 ..< self.items.count) {
    
                if (self.items[i].id == id) {
                    self.items[i].name = value
                    break
                }
    
            }
     
        }
    
    }
swift

1 个回答

  1. Best Answer

    采用递归方法怎么样：

    import Foundation

struct ItemType: Identifiable {
    let id: UUID
    var name: String
    var nestedItems: [ItemType]

    init(name: String, nestedItems: [ItemType] = []) {
        self.id = UUID()
        self.name = name
        self.nestedItems = nestedItems
    }
}

class ItemModel {
    var items: [ItemType]

    init(items: [ItemType]) {
        self.items = items
    }

    func updateName(id: UUID, newName: String) {
        updateNameRecursively(id: id, newName: newName, items: &self.items)
    }

    private func updateNameRecursively(id: UUID, newName: String, items: inout [ItemType]) {
        for i in 0..<items.count {
            if items[i].id == id {
                items[i].name = newName
                return 
            } else {
                updateNameRecursively(id: id, newName: newName, items: &items[i].nestedItems)
            }
        }
    }
}

extension ItemModel {
    func prettyPrintItems(items: [ItemType], indentLevel: Int = 0) {
        let indent = String(repeating: "  ", count: indentLevel)
        for item in items {
            print("\(indent)- \(item.name) (id: \(item.id))")
            prettyPrintItems(items: item.nestedItems, indentLevel: indentLevel + 1)
        }
    }
}

let item0 = ItemType(name: "item0")
let item1 = ItemType(name: "item1")
let item2 = ItemType(name: "item2", nestedItems: [item1])
let item3 = ItemType(name: "item3", nestedItems: [item2])
let item4 = ItemType(name: "item4")
let item5 = ItemType(name: "item5", nestedItems: [item4])
let model = ItemModel(items: [item0, item3, item5])
print("Before:")
model.prettyPrintItems(items: model.items)
model.updateName(id: item1.id, newName: "item1 updated!")
model.updateName(id: item2.id, newName: "item2 updated!")
model.updateName(id: item4.id, newName: "item4 updated!")
print("After:")
model.prettyPrintItems(items: model.items)

    如果你想使用字典而不是数组nestedItems：

    import Foundation

struct ItemType: Identifiable {
    let id: UUID
    var name: String
    var nestedItems: [String: ItemType]

    init(name: String, nestedItems: [String: ItemType] = [:]) {
        self.id = UUID()
        self.name = name
        self.nestedItems = nestedItems
    }
}

class ItemModel {
    var items: [String: ItemType]

    init(items: [ItemType]) {
        self.items = Dictionary(uniqueKeysWithValues: items.map { ($0.id.uuidString, $0) })
    }

    func updateName(id: UUID, newName: String) {
        updateNameRecursively(id: id.uuidString, newName: newName, items: &self.items)
    }

    private func updateNameRecursively(id: String, newName: String, items: inout [String: ItemType]) {
        if let item = items[id] {
            items[id]?.name = newName
        } else {
            for key in items.keys {
                updateNameRecursively(id: id, newName: newName, items: &items[key]!.nestedItems)
            }
        }
    }
}

extension ItemModel {
    func prettyPrintItems(items: [String: ItemType], indentLevel: Int = 0) {
        let indent = String(repeating: "  ", count: indentLevel)
        for item in items.values {
            print("\(indent)- \(item.name) (id: \(item.id))")
            prettyPrintItems(items: item.nestedItems, indentLevel: indentLevel + 1)
        }
    }
}

let item0 = ItemType(name: "item0")
let item1 = ItemType(name: "item1")
let item2 = ItemType(name: "item2", nestedItems: [item1.id.uuidString: item1])
let item3 = ItemType(name: "item3", nestedItems: [item2.id.uuidString: item2])
let item4 = ItemType(name: "item4")
let item5 = ItemType(name: "item5", nestedItems: [item4.id.uuidString: item4])
let model = ItemModel(items: [item0, item3, item5])
print("Before:")
model.prettyPrintItems(items: model.items)
model.updateName(id: item1.id, newName: "item1 updated!")
model.updateName(id: item2.id, newName: "item2 updated!")
model.updateName(id: item4.id, newName: "item4 updated!")
print("After:")
model.prettyPrintItems(items: model.items)

    示例输出：

    Before:
- item0 (id: CE42EA37-3841-4D4C-931D-0611FC80E1F0)
- item3 (id: 0EADCD5E-C24B-495A-9581-97DEC427B859)
  - item2 (id: 44103D4A-0871-4235-B895-4AD16C3AABB0)
    - item1 (id: 0412FC6B-B5A4-4AFB-8BF4-C4569EBA16E7)
- item5 (id: 4C396B6A-1FA7-4E7B-AE6C-EE4B10395AB6)
  - item4 (id: 5CA53EA0-D229-429C-812E-A364EE725B89)
After:
- item0 (id: CE42EA37-3841-4D4C-931D-0611FC80E1F0)
- item3 (id: 0EADCD5E-C24B-495A-9581-97DEC427B859)
  - item2 updated! (id: 44103D4A-0871-4235-B895-4AD16C3AABB0)
    - item1 updated! (id: 0412FC6B-B5A4-4AFB-8BF4-C4569EBA16E7)
- item5 (id: 4C396B6A-1FA7-4E7B-AE6C-EE4B10395AB6)
  - item4 updated! (id: 5CA53EA0-D229-429C-812E-A364EE725B89)
    • 1

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